Swinging arm support



Jan. 2o, 1942. R. G. BIRR 2,270,250 f SWINGING ARM SUPPORT l Y FiledSept. l2, 1940 2 Sheets-SheecI l `Jan. 20, 1942*, 'R Q BIRR 2,270,250

SWIINGING ARM SUPPORT Filed Sept. l2, 1940 2 Sheets-SheetI 2 21f'zveizor l #BZyadoZ/oz l. .55'79" MJ M @d j/lorngs,

Patented Jan. 20, 1942 NT orties SWINGING ARM SUPPORT.

Rudolph G. Birr, Lmbard,.lll., assignor to Precision Metal Worke tion ofIllinois s, Chicago, Illi., a. corpora- Applicatin september 12, 1940,serial 10.356,414- sciaims. (c1. 248-281) The inventionrelates tofimprovements in sup-- portsI of. the` so-called swinging or folding, armtype.` Such` supports may be used for a wide variety ot purposes,A asfor example, for holding reading lamps, spotlights; instrument traysand, almost'any number of other devices.

, One importantobjectotv the present invention.

isto. providea sturdy support ofthe type described, which is` especiallyadapted for low-cost quantity production.

Another object. is. to` provide a support/of the type` indicated. whichcany bei` swung withV free-- dom. througha wide. arcl ot. adjustment andwhich.

embodiesV a novel and simple arrangement for efectually holding it in.aselected position of ad.- justment.

Further objects and advantages of the invention will become apparent asthe. following description proceeds taken. in connection with theaccompanying drawings, in. which:

Figure 1` is ,a side elevation of. a lamp stand. comprising a, swingingarm` embodying. myin-y vention, they arm being shown in full lines. atone extremity of itsvadjusting movement and in dot'- d'ash lines` at theother extremityr of such movement.

Fig. 2 is an enlarged fragmentary detail side` View of the` swinging`arm.

Fig. 3 is a lower edge View of the left hand, portion of the arm.

Fig. 4 is a transverse ajl'ong` the line `4 4' in Fig.

Fig. 5 isA an exploded swinging arm.

Fig. 6` is a sideV elevation,.partially broken, of a modified formofswinging arm embodyingv the invention.

Fig. '7 is anenlarged detail alongV the line 'I-l in Fig. 6?.

Fig. 8 is a side elevation, parts broken away, of aA second: modifiedform of. swinging. arm. embodying' the invention.

Figi. 9J is an; enlarged detail.' transverse sectional. view takensubstantially alongr the line 9-9 in` Fig. 8.

Though but three particular embodiments; of the invention have been.described. and. shown herein, itwillA be apparent to those` skilled inthe art that a number of other modifications and sectional' view taken2. perspective view of the sectional view` takenalternativearrangements. may be used. without departing from the invention..Consequently, the detailed description herein of thgparticular specificembodiments shown is not intended to be limiting in character, but, ontheother hand, I

intend to cover allv modifications and alternative 651 A with portionsof the constructions falling` within the spirit and scope of theyinvention as expressed in the appended claims. v

In thefirst exemplary embodiment, my inven- 1, tion has been shown(Fig. 1) as applied to a support for an electric lamp. The support showncomprises a. swinging arm mechanism I0 embodying my invention, mountedon a suitable standard II.` and carrying on its free or outer end a lampbase I-2 with the usual shade I3. The arm can be adjustably positionedeither horizontally, as shown in full lines, vertically as` shown. indot-dash lines-,or in any desired intermediate position.- I-t will beappreciated that a suitable decorative sleeve or the like, not shown,may be telescoped over the arm I0 to conceal it when occasion requires.

The arm I0 comprises a linkage of what is commonly known as theparallelogram type. It includes two long links I4. I5 in the form ofrigid metal bars presenting fiat side faces (Figs. 2 to 5). Theselinksare disposed in parallel edge to edge relation, and; in the courseof swinging movement of the arm, shift rela-tive to each other in alongitudinal direction. At their opposite ends the links arecross-linked together to complete the parallelogramY linkage. In thepresent instance the cross linkage is formed by two metal yokes I6, I1having disk shaped jaws between which the linksl are` respectively (Fig.2'). The'yoke II at the inner end of the arm may be rigidly fastened tothe standard II, while the other yoke I6 is rigidly fastened to the lampbase I2.

Upon reference to Fig. 2 it will be observed that in the operation ofthe parallelogram linkage, when the arm I0 is vin its horizontalposition, the lowermost link I5 is displaced longitudinally outward withrespect to the upper link I4. On the other hand, when the linkage isswung to upright position this relation is reversed so that-the linkI4is now displaced longitudinally upward from the other link I5. Attheir 45 angle position (shown in dot-dash lines in Fig. 2), or in otherwords, midway between vertical and horizontal, the two links I4; I5 are-exactly matched as to endwise position'. It is to be observed also thatwhenv the arm I0 is either in its horizontal or-vertical position, thelinks go solid tively limiting the range of arm movement and that theyhave their maximum lateral displacementy relativeto each other when thearm I0 is in its midway position.

Inl-order to` hold. the arm Ill inv any selected pivoted at I3, I9 and20, 21

position of angular adjustment intermediate its extreme vertical endhorizontal positions or in such extreme positions, a novel frictionaltype gripping means has been provided for the links. Upon reference toFigs. 2 to 5 it will be seen that this means comprises two rectangulargripper plates or portions 22 of resilient sheet metal arranged tooverlie opposite at faces of the pair of links I4, |5. The sheet metalplates 22 are of a width sufficient completely to embrace the links evenwhen the latter are spread apart a maximum distance, this latter pointoccurring when the arm is in its 45 or midwayposition of adjustment (seedot-dash line position of Fig.2).

To draw the sheet metal gripper plates 22 snugly against the flat facesof the pair of links I4, I5 a series of bolts 23 are used. These boltspass through complemental elongated notches 24,

25 in the opposed edges of the links |4 and I5, respectively (Figs. 2and 5). The notches are of such length that when the linkage is in itshorizontal position the Shanks of the bolts 23 are received between theoverlapping right hand ends of the notches 25 in the lower link I5 andleft hand ends of the notches 24 of the upper link I4. Conversely, whenthe linkage is in its upright position the shanks of the bolts 23 arereceived between the overlapping opposite ends of the notches 24, 25.Preferably the gripper plates 22 are bowedv outwardly slightly alongtheir longitudinal center lines (see Figs. 4 and 5) as indicated at 26,`and are bowed toward each other along longitudinal lines lying on eachside of their centers. In this way a rm frictional grip on each of thelinks I4, I5 is assured in any position of angular adjustment for thearm IIJ. This frictional grip of the plates 22 on the links I4, I5yieldably resists of motion of the latter relative to each other bothlaterally and longitudinally. The bolts 23 are drawn up tight enough sothat any expected load carried by the arm will not cause the latter toswing inadvertently, though leaving the linkage free enough that it canbe pulled into a desired position by a user.

Those familiar vv ith metal work will appreciate at oncek the simplicityof the manufacturing operations required in making the parts for theswinging arm described above. The bolts 23 are, of course, standardscrew machine parts. while the gripper plates 22 can be fashioned asmetal stampings, the links I4, I5 cut from ordinary bar stock and theyokes I6, I'I made as simple castings. Despite this extreme simplicityand low cost very effective operation is achieved as well as athoroughly sturdy construction. In connection with the operation observeparticularly that the frictional grip of the resilient sheet metalplates 22 throughout substantially the entire length of the links I4, I5insures that the links will be properly held against relativedisplacement in any particular angle of adjustment and yet the arm I0can be swung, without the application of too excessive a force, to movethe. linkage.

In Figs. 6 and l I have illustrated a modified form of the swinging armsupport ma, which may be used in substantially the same manner as thearm ID described above. The arm Illa resembles the arm I0 in that italso comprises a parallelogram type of linkage including two elongatedlinks Illa, I5u made of flat bar stock arranged edge to edge to presentflat side faces and pivoted at their ends on yokes I6, I1 identical withthose described above, like reference numerals having been used for likeparts. In the present instance, however, releasable retention of thelinkage in various positions of angular adjustment is accomplished bymeans of a single piece of sheet metal 2'?.a folded upon itself to formthe two opposed portions overlying the opposite side faces of the linksI4, I5a and resiliently gripping the link |42. Three screws 23a fix thefolded metal sheet 22a to the other link I5a.

In order to define predetermined angular adjustment positions withparticularity for the arm I0, transverse grooves 3|) are formed in thelink I4a and complemental ribs 3| are stamped in the opposed oroverlapping portion of the sheet metal gripper plate 22a to ride intothese grooves. Three such sets of grooves 30 have been shown (Fig. 6) onone side of the link I4a with three grooves in each set and acooperating rib for each set in the plate 22a. The ribs 3| enter intothe corresponding one of the cooperating end grooves 30 in theassociated set when the arm Illa is in its respective two extremepositions, which are apart, and into the center groove of the associatedset when the arm is in its halfway or 45 position. Of course, notchescorresponding to other positions can be provided if desired. This riband groove arrangement affords distinct and precise locating of theswinging arm I0a in the corresponding angular position. As the arm isswung between these positions the ribs 3| rub frictionally on the linkI4a, however, so that the linkage is also releasably retained in anydesired intermediate position in which it may be left. At all times theunribbed portion or jaw of the gripper plate 22a engages the link I4africtionally throughout substantially the entire length of the latter,thereby yieldably resisting linkage movement.

In Figs. 8 and 9 I have shown still another modified form of swingingarm Illb also embodying my invention. This arm Illb is substantiallylike the arm Illa described above except that the positions ofadjustment are defined by longitudinal rather than transverse ribs andgrooves on the opposed portions of the sliding parts. Thus the linkageagain comprises bar links |4b, I5b pivoted to yokes I6, I1 and, as inthe case of the arm |05, a resilient sheet metal plate 22b folded aboutand screwed to the link I5b with its opposed side portions embracing thelink |4b. By using longitudinal rather than transverse grooves and ribs,however, I am able to define three positions of adjustment with only twoinstead of three grooves as before. In the construction shown in Figs. 8and 9 two longitudinal grooves 32 are fashioned in the link I4b and alongitudinal rib 33 in the gripper plate 221. Thus when the linkage isin either of its two extreme positions the links |411, I5b abut edge toedge and the rib 33 is seated in the upper (as viewed in Figs. 8 and 9)of the grooves 32. But when the linkage is in its midway position, withthe links spread apart a maximum distance, the rib 33 is seated in theother or lower groove 32 (see dotdash line position in Fig. 9).

I claim as my invention:

l. In a swinging arm support, the combination with a parallelogram typeof linkage including two elongated parallel links of bar form presentingflat side faces, of means including two portions of resilient sheetmetal overlying the respective opposite fiat Side faces of said linksthroughout a major portion of the latters length and engaging the samefor releasably holding the links in adjusted positions of endwisedisplacement relative to each other.

2. In an adjustable support of the type described, the combination witha parallelogram type of linkage including two elongated side-bysidelinks, of means resiliently and frictionally engaging at least one ofsaid links substantially throughout the latters length for yieldablyrestraining said links against movement relative to each other, andmeans for limiting endwise displacement of said rst mentioned meansrelative to the links.

3. Ina swinging arm support, the combination of a parallelogram type oflinkage including two elongated parallel links and means pivotallyinterconnecting them at their opposite ends to move into abuttingside-by-side relationship at the respective extremities of swingingmovement of linkage, each of said links having an elongated notch in theside thereof opposed to the other and said notches being located foroverlapping of their opposite end portions when the linkage is inrespective ones of its extremities of movement, gripper means includinga pair of opposed members located on opposit-e sides of said pair oflinks, and means passing through said notches for drawing said memberstoward each other into frictional engagement with both of said links.

4. In a swinging arm support, the combination of a parallelogram type oflinkage including two links arranged side-by-side and of bar formpresenting fiat side faces and means pivotally interconnecting them attheir opposite ends to move into abutting edge-to-edge relationship atthe respective extremities of swinging movement of the linkage, each ofsaid links having an elongated notch in the edge thereof opposed to theother, said notches being located for overlapping of their opposite endportions when the linkage is in respective ones of its extremities ofmovement, a pair of opposed resilient sheet metal gripper platesengaging opposite side faces of both of said links, and means passingthrough said notches for drawing said plates toward each other intofrictional engagement with said links, each of said plates engaging eachof said links substantially throughout the length of the latter.

5. In a swinging arm support, the combination of a. parallelogram typeof linkage including two elongated parallel links of bar form presentingflat side faces, a gripper plate in the form of a portion vof resilientsheet metal doubled upon itself yand embracing the links, said gripperplate being fixed to one of said links while frictionally engaging theside faces of the other, and mating ribs and grooves on the engagingportions of said other link and gripper plate for releasably holdingsaid links against relative movement when in predetermined positions ofadjustment relative to each other.

6. In a swinging arm support, the combination or" a, parallelogram typeof linkage including two elongated parallel links, a resilient sheetmetal plate xed to one of said links and overlying a side of the otherand pressed against the same to frictionally engage it, the engagingportions of said other link and plate having mating ribs and groovesthereon transverse to the links for releasably holding the links againstrelative longitudinal movement in corresponding predetermined positionsof linkage adjustment.

'7. In a swinging arm support, the combination of a parallelogram typeof linkage including two elongated parallel links ofbar form presentingiiat side faces, a gripper comprising two portions of resilient sheetmetal disposed on opposite sides of the links and iixed to one of saidlinks, one of said portions of sheet metal being arranged frictionallyto engage the other link substantially throughout the latters length,the other portion of sheet metal and said other link havinglongitudinally extending mating ribs Vand grooves thereon for releasablyholding the links against relative lateral movement in correspondingpredetermined positions of linkage adjustment.

8. In a swinging arm support, the 'combination of a parallelogram typeof linkage including two elongated parallel links, a member fixed to oneof said links and arranged to overlie a portion of the other, and theoverlying portions of said other link and said member having enga-gingelements thereon extending longitudinally of said other link forreleasably holding the links against relative lateral movement incorresponding predetermined positions of linkage adjustment.

I RUDOLPH G. BIER.

